class_docstr: A DataShape parser object.
class_docstr_tok: ["A","DataShape","parser","object","."]
docstr: type_kwarg : NAME_LOWER EQUAL type_arg
  
  Returns a (name, type_arg) tuple, or None.
docstr_tok: ["type_kwarg",":","NAME_LOWER","EQUAL","type_arg","Returns","a","(","name",",","type_arg",")","tuple",",","or","None","."]
code: def parse_type_kwarg(self):
      """
      type_kwarg : NAME_LOWER EQUAL type_arg
  
      Returns a (name, type_arg) tuple, or None.
      """
      if self.tok.id != lexer.NAME_LOWER:
          return None
      saved_pos = self.pos
      name = self.tok.val
      self.advance_tok()
      if self.tok.id != lexer.EQUAL:
          self.pos = saved_pos
          return None
      self.advance_tok()
      arg = self.parse_type_arg()
      if arg is not None:
          return (name, arg)
      else:
          # After "NAME_LOWER EQUAL", a type_arg is required.
          self.raise_error("Expected a type constructor argument")
  
imports: from __future__ import absolute_import, division, print_function
  from .None import lexer, error
  from .None import coretypes
label_desc: Use image node_id 13 for calling the DataShapeParser obj's underlying member method code with example usage: obj.parse_type_kwarg() and returns: None, None, name,  arg