code: def p_param_substitution(self, p):
          'param_substitution : ID EQUALS rvalue'
          p[0] = (p[1], p[3])
          p.set_lineno(0, p.lineno(1)f p_param_substitution(self, p):
          'param_substitution : ID EQUALS rvalue'
          p[0] = (p[1], p[3])
          p.set_lineno(0, p.lineno(1))
docs: param_substitution : ID EQUALS rvalue