pub(super) const REQUIRED_LOOP: &str = " for column in required {\n\
\x20 let value = row[column]\n\
\x20 if value == nil {\n\
\x20 return Err(\"{MODEL}.{column} is required\")\n\
\x20 }\n\
\x20 }\n";
pub(super) const KIND_LOOP: &str = " for column in kinds.keys() {\n\
\x20 let value = row[column]\n\
\x20 // A nil is absence, which the required check above already ruled on.\n\
\x20 if value != nil && type_of(value) != kinds[column] {\n\
\x20 return Err(\"{MODEL}.{column} must be \" + kinds[column])\n\
\x20 }\n\
\x20 }\n\n";