<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse(s):
 """Parse a string representation back into the Vector. DenseVector([2.0, 1.0, 2.0]) SparseVector(100, {0: 2.0}) """

        if s.find('(') == -1 and s.find('[') != -1:
            return DenseVector.parse(s)
        elif s.find('(') != -1:
            return SparseVector.parse(s)
        else:
            raise ValueError(
                "Cannot find tokens '[' or '(' from the input string.")