def p_blocking_substitution_base(self, p):
        'blocking_substitution_base : delays lvalue EQUALS delays rvalue'
        p[0] = BlockingSubstitution(p[2], p[5], p[1], p[4], lineno=p.lineno(2))
        p.set_lineno(0, p.lineno(2))
blocking_substitution_base : delays lvalue EQUALS delays rvalue