function signature( alias ) {
	var out;
	var i;
	if ( !isString( alias ) ) {
		throw new TypeError( format( 'invalid argument. Must provide a string. Value: `%s`.', alias ) );
	}
	out = [];
	for ( i = 0; i < ALIAS_TO_SIGNATURE.length; i++ ) {
		if ( ALIAS_TO_SIGNATURE[ i ][ 0 ] === alias ) {
			out.push( ALIAS_TO_SIGNATURE[ i ][ 1 ] );
		}
	}
	return ( out.length ) ? out : null;
}
Returns the signature(s) associated with a specified alias.

@param {string} alias - alias
@throws {TypeError} must provide a string
@returns {(StringArray|null)} signature(s)

@example
var out = signature( 'base.sin' );
// returns [ '...' ]