/// Encode a map to JSON
/// @access private
/// @param {Map} $map - map to be encoded
/// @return {String} - encoded map
/// @require {function} _proof-quote
/// @require {function} json-encode
@function _json-encode--map($map) {
  $str: "";

  @each $key, $value in $map {
    $str: $str + ', ' + _proof-quote($key) + ': ' + json-encode($value);
  }

  @return '{' + str-slice($str, 3) + '}';
}