def _flatten_string_key_value_pair(self, k, v, data):
    'Flatten string key/value pairs only.'
    if (not util.is_picklable(k, v)):
        return data
    if self.keys:
        if (not isinstance(k, string_types)):
            return data
        elif k.startswith(tags.JSON_KEY):
            k = self._escape_key(k)
    else:
        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 string key/value pairs only.
def _flatten_string_key_value_pair(self, k, v, data):
    
    if (not util.is_picklable(k, v)):
        return data
    if self.keys:
        if (not isinstance(k, string_types)):
            return data
        elif k.startswith(tags.JSON_KEY):
            k = self._escape_key(k)
    else:
        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