TypeRepresentation:a.pythonTypeRepresentation
  PyFunctionTypeRepresentation
    PyTypeParameterList
      PsiElement(Py:LBRACKET)('[')
      PyTypeParameter
        PsiElement(Py:EXP)('**')
        PsiElement(Py:IDENTIFIER)('P')
      PsiElement(Py:RBRACKET)(']')
    PyParameterListRepresentation
      PsiElement(Py:LPAR)('(')
      PyNamedParameterTypeRepresentation('x')
        PsiElement(Py:IDENTIFIER)('x')
        PsiElement(Py:COLON)(':')
        PsiWhiteSpace(' ')
        PyReferenceExpression: int
          PsiElement(Py:IDENTIFIER)('int')
      PsiElement(Py:RPAR)(')')
    PsiWhiteSpace(' ')
    PsiElement(Py:RARROW)('->')
    PsiWhiteSpace(' ')
    PyNoneLiteralExpression
      PsiElement(Py:NONE_KEYWORD)('None')