'Adds an input to the Form object. Input examples:
<INPUT type="text" name="email"><BR>
<INPUT type="radio" name="sex" value="Male"> Male<BR>
:param attrs: attrs=[("class", "screen")]'

def add_field_by_attrs(self, attrs):

    (should_add_new, form_field) = self.form_field_factory(attrs)
    if (form_field is None):
        return None
    if should_add_new:
        self.add_form_field(form_field)
    return form_field
