def _flatten_key_value_pair(self, k, v, data):
    'Flatten a key/value pair into the passed-in dictionary.'
    if (not util.is_picklable(k, v)):
        return data
    if (k is None):
        k = 'null'
    if (self.numeric_keys and isinstance(k, numeric_types)):
        pass
    elif (not isinstance(k, string_types)):
        try:
            k = repr(k)
        except Exception:
            k = compat.ustr(k)
    data[k] = self._flatten(v)
    return data
Flatten a key/value pair into the passed-in dictionary.
def _flatten_key_value_pair(self, k, v, data):
    
    if (not util.is_picklable(k, v)):
        return data
    if (k is None):
        k = 'null'
    if (self.numeric_keys and isinstance(k, numeric_types)):
        pass
    elif (not isinstance(k, string_types)):
        try:
            k = repr(k)
        except Exception:
            k = compat.ustr(k)
    data[k] = self._flatten(v)
    return data