code: def p_example_field_ref(self, p):
          'example_field : ID EQ ID NL'
          p[0] = AstExampleField(self.path, p.lineno(1), p.lexpos(1),
              p[1], AstExampleRef(self.path, p.lineno(3), p.lexpos(3), p[3])f p_example_field_ref(self, p):
          'example_field : ID EQ ID NL'
          p[0] = AstExampleField(self.path, p.lineno(1), p.lexpos(1),
              p[1], AstExampleRef(self.path, p.lineno(3), p.lexpos(3), p[3]))
docs: example_field : ID EQ ID NL