lib/core/utils.js
function(array, ind) {
    if (ind >= array.length || ind < 0) 
      throw new Error('$' + (ind + 1) + ': argument number out of range')
    return array[ind]
  }
function(array, ind) {
    if (ind >= array.length || ind < 0) 
      throw new Error('$' + (ind + 1) + ': argument number out of range')
    return array[ind]
  }
function ( array , ind ) { if ( ind >= array . length || ind < 0 ) throw new Error ( '$' + ( ind + 1 ) + ': argument number out of range' ) return array [ ind ] }
Simple helper to throw en error if the index is out of range
Simple helper to throw en error if the index is out of range