<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def map_keys(pvs, keys):
 """ Add human readable key names to dictionary while leaving any existing key names. """

    rs = []
    for pv in pvs:
        r = dict((v, None) for k, v in keys.items())
        for k, v in pv.items():
            if k in keys:
                r[keys[k]] = v
            r[k] = v
        rs.append(r)
    return rs