string_isalpha(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1 &&
        isalpha(*p))
        return PyBool_FromLong(1);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
        return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    for (; p < e; p++) {
        if (!isalpha(*p))
            return PyBool_FromLong(0);
    }
    return PyBool_FromLong(1);
}
Unknown