code: function prependUntilLength (str, len, char) {
    if (str.length >= len) 
      return str
    else 
      return prependUntilLength(str=char+str, len, char)
  }
docs: Prepends `char` to `str` until it's length is `len`
  
  @param {String} str
  @param {Number} len
  @param {String} char
  @return {String}
  @api private