>>> from expressions import well_parenthesized_1

>>> well_parenthesized_1('((x+2)*(3*r/z)))')
False
>>> well_parenthesized_1('(f(x)))(5*x-y)')
False
>>> well_parenthesized_1('((x+2)*(((3*r/z))')
False
>>> well_parenthesized_1('((x+2)*(3*r/z))')
True