old_contents: from sympy.core import Function, Pow, sympify
  from sympy.polys import Poly
  
  
  def decompogen(f, symbol):
      """
      Computes General functional decomposition of ``f``.
      Given an expression ``f``, returns a list ``[f_1, f_2, ..., f_n]``,
      where::
                f = f_1 o f_2 o ... f_n = f_1(f_2(... f_n))
  
      Note: This is a General decomposition function. For Polynomial
      decomposition see ``decompose`` in polys.
  
      Examples
      ========
  
      >>> from sympy.solvers.decompogen import decompogen
      >>> from sympy.abc import x
      >>> from sympy import sqrt, sin, cos
      >>> decompogen(sin(cos(x)), x)
      [sin(x), cos(x)]
      >>> decompogen(sin(x)**2 + sin(x) + 1, x)
      [x**2 + x + 1, sin(x)]
      >>> decompogen(sqrt(6*x**2 - 5), x)
      [sqrt(x), 6*x**2 - 5]
  
      """
      f = sympify(f)
  
      # ===== Simple Functions ===== #
      if isinstance(f, (Function, Pow)):
          return [f.subs(f.args[0], symbol), f.args[0]]
  
      # ===== Convert to Polynomial ===== #
      fp = Poly(f)
      gens = fp.gens
  
      if len(gens) == 1:
          f1 = f.subs(gens[0], symbol)
          f2 = gens[0]
          return [f1, f2]
  
new_contents: from sympy.core import Function, Pow, sympify
  from sympy.polys import Poly
  
  
  def decompogen(f, symbol):
      """
      Computes General functional decomposition of ``f``.
      Given an expression ``f``, returns a list ``[f_1, f_2, ..., f_n]``,
      where::
                f = f_1 o f_2 o ... f_n = f_1(f_2(... f_n))
  
      Note: This is a General decomposition function. For Polynomial
      decomposition see ``decompose`` in polys.
  
      Examples
      ========
  
      >>> from sympy.solvers.decompogen import decompogen
      >>> from sympy.abc import x
      >>> from sympy import sqrt, sin, cos
      >>> decompogen(sin(cos(x)), x)
      [sin(x), cos(x)]
      >>> decompogen(sin(x)**2 + sin(x) + 1, x)
      [x**2 + x + 1, sin(x)]
      >>> decompogen(sqrt(6*x**2 - 5), x)
      [sqrt(x), 6*x**2 - 5]
  
      """
      f = sympify(f)
  
      # ===== Simple Functions ===== #
      if isinstance(f, (Function, Pow)):
          return [f.subs(f.args[0], symbol), f.args[0]]
  
      # ===== Convert to Polynomial ===== #
      fp = Poly(f)
      gens = fp.gens
  
      if len(gens) == 1:
          f1 = f.subs(gens[0], symbol)
          f2 = gens[0]
          return [f1, f2]
  
      return [f]
  
subject: Return `f` if no decomposition