mystery.js

var fs = require("fs");

function inc(p, q){
   if(q == 77 ) q =1;
   if( p < -100 )
   {
   	p = -p;
   }
   return p + q/q;
}

function weird(x,y,z, mode)
{
    if( x > 87 && y < 70 )
    {
        z = 33;
    }    
    else if( z < 42 )
    {
        if( mode == "strictly" )
        {
            return 0;
        }
        else if( mode.indexOf("bob") == 0 )
        {
            return 1;
        }
    }
    else
    {
        if( mode != "stricter" )
        {
            return y = z / x;
        }
    }
    return 1;
}


function fileTest(filePath, dir)
{
	if (!fs.existsSync(dir)){

   	    return false;
    }
    
    var files = fs.readdirSync(dir);
    if( files.length == 0 )
    {
        return false;
    }

   if( fs.existsSync(filePath ))
   {
		var buf = fs.readFileSync(filePath, "utf8");
		if( buf.length > 0 )
		{
			return true;
		}
		return false;
	}
}

function normalize(phoneNumber) {

    return phoneNumber.replace(
      /^[\+\d{1,3}\-\s]*\(?([0-9]{3})\)?[-. ]?([0-9]{3})[-. ]?([0-9]{4})$/,
      "$1$2$3"
    );

}

function format(phoneNumber, formatString, options) 
{
    // Normalize the phone number first unless not asked to do so in the options
    if (!options || !options.normalize) {
      phoneNumber = normalize(phoneNumber)
    };

    for ( var i = 0, l = phoneNumber.length; i < l; i++ ) {
      formatString = formatString.replace("N", phoneNumber[i]);
    }
  
    return formatString;

}

function blackListNumber(phoneNumber)
{
	var num = format(phoneNumber, "(NNN) NNN-NNNN");
	var area = num.substring(1,4);
	if( area != "919" )
	{
		return true;
	}
	return false;
}

exports.fileTest = fileTest;
exports.normalize = normalize;
exports.format = format;
exports.inc = inc;
exports.weird = weird;
exports.blackListNumber = blackListNumber;