<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def merge_dict(lhs, rhs):
 """ Merge content of a dict in another :param: dict: lhs dict where is merged the second one :param: dict: rhs dict whose content is merged """

    assert isinstance(lhs, dict)
    assert isinstance(rhs, dict)
    for k, v in rhs.iteritems():
        if k not in lhs:
            lhs[k] = v
        else:
            lhs[k] = merge_dict(lhs[k], v)
    return lhs