old_contents: """Utility to compile possibly incomplete Python source code."""
  
  import sys
  import traceback
  
  __all__ = ["compile_command"]
  
  def compile_command(source, filename="<input>", symbol="single"):
      r"""Compile a command and determine whether it is incomplete.
  
      Arguments:
  
      source -- the source string; may contain \n characters
      filename -- optional filename from which source was read; default "<input>"
      symbol -- optional grammar start symbol; "single" (default) or "eval"
  
      Return value / exceptions raised:
  
      - Return a code object if the command is complete and valid
      - Return None if the command is incomplete
      - Raise SyntaxError or OverflowError if the command is a syntax error
        (OverflowError if the error is in a numeric constant)
  
      Approach:
  
      First, check if the source consists entirely of blank lines and
      comments; if so, replace it with 'pass', because the built-in
      parser doesn't always do the right thing for these.
  
      Compile three times: as is, with \n, and with \n\n appended.  If
      it compiles as is, it's complete.  If it compiles with one \n
      appended, we expect more.  If it doesn't compile either way, we
      compare the error we get when compiling with \n or \n\n appended.
      If the errors are the same, the code is broken.  But if the errors
      are different, we expect more.  Not intuitive; not even guaranteed
      to hold in future releases; but this matches the compiler's
      behavior from Python 1.4 through 1.5.2, at least.
  
      Caveat:
  
      It is possible (but not likely) that the parser stops parsing
      with a successful outcome before reaching the end of the source;
      in this case, trailing symbols may be ignored instead of causing an
      error.  For example, a backslash followed by two newlines may be
      followed by arbitrary garbage.  This will be fixed once the API
      for the parser is better.
  
      """
  
      # Check for source consisting of only blank lines and comments
      for line in source.split("\n"):
          line = line.strip()
          if line and line[0] != '#':
              break               # Leave it alone
      else:
          source = "pass"         # Replace it with a 'pass' statement
  
      err = err1 = err2 = None
      code = code1 = code2 = None
  
      try:
          code = compile(source, filename, symbol)
      except SyntaxError, err:
          pass
  
      try:
          code1 = compile(source + "\n", filename, symbol)
      except SyntaxError, err1:
          pass
  
      try:
          code2 = compile(source + "\n\n", filename, symbol)
      except SyntaxError, err2:
          pass
  
      if code:
          return code
      try:
          e1 = err1.__dict__
      except AttributeError:
          e1 = err1
      try:
          e2 = err2.__dict__
      except AttributeError:
          e2 = err2
      if not code1 and e1 == e2:
          raise SyntaxError, err1
  
new_contents: """Utility to compile possibly incomplete Python source code."""
  
  __all__ = ["compile_command"]
  
  def compile_command(source, filename="<input>", symbol="single"):
      r"""Compile a command and determine whether it is incomplete.
  
      Arguments:
  
      source -- the source string; may contain \n characters
      filename -- optional filename from which source was read; default "<input>"
      symbol -- optional grammar start symbol; "single" (default) or "eval"
  
      Return value / exceptions raised:
  
      - Return a code object if the command is complete and valid
      - Return None if the command is incomplete
      - Raise SyntaxError or OverflowError if the command is a syntax error
        (OverflowError if the error is in a numeric constant)
  
      Approach:
  
      First, check if the source consists entirely of blank lines and
      comments; if so, replace it with 'pass', because the built-in
      parser doesn't always do the right thing for these.
  
      Compile three times: as is, with \n, and with \n\n appended.  If
      it compiles as is, it's complete.  If it compiles with one \n
      appended, we expect more.  If it doesn't compile either way, we
      compare the error we get when compiling with \n or \n\n appended.
      If the errors are the same, the code is broken.  But if the errors
      are different, we expect more.  Not intuitive; not even guaranteed
      to hold in future releases; but this matches the compiler's
      behavior from Python 1.4 through 1.5.2, at least.
  
      Caveat:
  
      It is possible (but not likely) that the parser stops parsing
      with a successful outcome before reaching the end of the source;
      in this case, trailing symbols may be ignored instead of causing an
      error.  For example, a backslash followed by two newlines may be
      followed by arbitrary garbage.  This will be fixed once the API
      for the parser is better.
  
      """
  
      # Check for source consisting of only blank lines and comments
      for line in source.split("\n"):
          line = line.strip()
          if line and line[0] != '#':
              break               # Leave it alone
      else:
          source = "pass"         # Replace it with a 'pass' statement
  
      err = err1 = err2 = None
      code = code1 = code2 = None
  
      try:
          code = compile(source, filename, symbol)
      except SyntaxError, err:
          pass
  
      try:
          code1 = compile(source + "\n", filename, symbol)
      except SyntaxError, err1:
          pass
  
      try:
          code2 = compile(source + "\n\n", filename, symbol)
      except SyntaxError, err2:
          pass
  
      if code:
          return code
      try:
          e1 = err1.__dict__
      except AttributeError:
          e1 = err1
      try:
          e2 = err2.__dict__
      except AttributeError:
          e2 = err2
      if not code1 and e1 == e2:
          raise SyntaxError, err1
  
subject: Remove useless imports, as reported by PyChecker.