Koha::Patron::Attribute - Koha Patron Attribute Object class
    my $attribute = Koha::Patron::Attribute->new({ code => 'a_code', ... });
    try { $attribute->store }
    catch { handle_exception };
    my $attribute = Koha::Patron::Attribute->new({ code => 'a_code', ... });
    if ( $attribute->opac_display ) { ... }
    my $attribute = Koha::Patron::Attribute->new({ code => 'a_code', ... });
    if ( $attribute->is_opac_editable ) { ... }
    my $attribute = Koha::Patron::Attribute->new({ code => 'a_code', ... });
    if ( $attribute->display_checkout ) { ... }
    my $description = $attribute->value_description
    Return authorised value description or free text based on attribute type settings
    my $description = $attribute->type_description
    Return description of attribute type
my $attribute_type = $attribute->type;
Returns a Koha::Patron::Attribute::Type object corresponding to the current patron attribute
_check_repeatable checks if the attribute type is repeatable and throws and exception if the attribute type isn't repeatable and there's already an attribute with the same code for the given patron.
_check_unique_id checks if the attribute type is marked as unique id and throws and exception if the attribute type is a unique id and there's already an attribute with the same code and value on the database.