old_contents: """
  Functions for sanitizing various strings to be used in a shell command.
  """
  
  from win_unc.internal.utils import take_while
  from win_unc.sanitizors import sanitize_username, sanitize_unc_path
  
  
  def is_valid_drive_letter(string):
      return (len(string) == 1          # Must be exactly one character long
              and string[0].isalpha())  # Must be an alphabet character (A through Z)
  
  
  def is_valid_unc_path(string):
      return (len(string) > 2                           # Must be at least 3 characters
              and take_while(lambda x: x == '\\', string) == ['\\', '\\']  # Must begin with `\\`
              and string == string.strip()              # Must not have surrounding white-space
              and string == sanitize_unc_path(string))  # Must not contain invalid characters
  
  
  def is_valid_username(string):
      """
      Returns `True` for valid Windows usernames (logons). A valid username is a non-empty string
      without certain characters (see `sanitize_username`).
      """
      return (len(string) > 0                           # Must not be empty
              and string == string.strip()              # Must not have surrounding white-space
              and string == sanitize_username(string))  # Must not contain invalid characters
  
new_contents: """
  Functions for sanitizing various strings to be used in a shell command.
  """
  
  from win_unc.internal.utils import take_while
  from win_unc.sanitizors import sanitize_username, sanitize_unc_path
  
  
  def is_valid_drive_letter(string):
      """
      Returns `True` if `string` represents a valid drive letter. Drive letters are exactly one
      character in length and between "A" and "Z". Case does not matter.
      """
      return (len(string) == 1          # Must be exactly one character long
              and string[0].isalpha())  # Must be an alphabet character (A through Z)
  
  
  def is_valid_unc_path(string):
      """
      Returns `True` if `string` is a valid UNC path. Valid UNC paths are at least three characters
      long, begin with "\\", do not start or end with whitepsace, and do not contain certain invalid
      characters (see `sanitize_unc_path`).
      """
      return (len(string) > 2                           # Must be at least 3 characters
              and take_while(lambda x: x == '\\', string) == ['\\', '\\']  # Must begin with `\\`
              and string == string.strip()              # Must not have surrounding white-space
              and string == sanitize_unc_path(string))  # Must not contain invalid characters
  
  
  def is_valid_username(string):
      """
      Returns `True` for valid Windows usernames (logons). A valid username is a non-empty string,
      that does not start or end with whitespace, and does not contain certain invalid characters
      (see `sanitize_username`).
      """
      return (len(string) > 0                           # Must not be empty
              and string == string.strip()              # Must not have surrounding white-space
              and string == sanitize_username(string))  # Must not contain invalid characters
  
subject: Add docstrings to validators