code: def p_assignment_expr(self, p):
          
          if len(p) == 2:
              p[0] = p[1]
          else:
              p[0] = ast.Assign(left=p[1], op=p[2], right=p[3])
docs: assignment_expr \
              : conditional_expr
              | left_hand_side_expr assignment_operator assignment_expr