'"merge" both maps and update the repetitions, the maps contain:
* Key:   word
* Value: number of repetitions'

def merge_maps(self, old_data, data, request, lang):

    msg = 'The    "%s"    parameter    must    be    a    dict,    got    "%s"    instead.'
    if (not isinstance(old_data, dict)):
        raise TypeError((msg % ('old_data', old_data.__class__.__name__)))
    if (not isinstance(data, dict)):
        raise TypeError((msg % ('data', old_data.__class__.__name__)))
    if (lang not in self.COMMON_WORDS.keys()):
        lang = 'unknown'
    for d in data:
        if ((len(d) >= 4) and d.isalnum() and (not d.isdigit()) and (d.lower() not in self.BANNED_WORDS) and (d.lower() not in self.COMMON_WORDS[lang]) and (not request.sent(d))):
            if (d in old_data):
                old_data[d] += data[d]
            else:
                old_data[d] = data[d]
    return old_data
