PyFile:shellAssignment1.py
  PyAssignmentStatement
    PyTargetExpression: my_files
      PsiElement(Py:IDENTIFIER)('my_files')
    PsiWhiteSpace(' ')
    PsiElement(Py:EQ)('=')
    PsiWhiteSpace(' ')
    PyEmptyExpression
      PsiElement(Py:SHELL_COMMAND)('!ls')