text: module.exports = function zeros(expression) {
    
    partsOfExp = expression.split('*')
  
    singleFactorials = []
    doubleFactorials = []
    partsOfExp.forEach(parseFactorial)
    factorials = []
    let result = BigInt(1)
    
    function parseFactorial(item) {
      if (item.match(/\d+!!/g)) {
        doubleFactorials.push(Number(item.match(/\d+/g)))
      } else {
        singleFactorials.push(Number(item.match(/\d+/g)))
      }
    }
  
    for (let index = 0; index < singleFactorials.length; index++) {
      factorials.push(doSingleFactorial(singleFactorials[index]))
    }
  
    for (let index = 0; index < doubleFactorials.length; index++) {
      factorials.push(doDoubleFactorial(doubleFactorials[index]))
    }
  
    function doSingleFactorial(number){
      return (BigInt(number) != BigInt(1)) ? BigInt(number) * doSingleFactorial(BigInt(number) - BigInt(1)) : BigInt(1);
    }
    function doDoubleFactorial(number){
      if (BigInt(number) % BigInt(2) === BigInt(0)) {
        return (BigInt(number) != BigInt(2)) ? BigInt(number) * doDoubleFactorial(BigInt(number) - BigInt(2)) : doSingleFactorial(BigInt(2));
      } else {
        return (BigInt(number) != BigInt(1)) ? BigInt(number) * doDoubleFactorial(BigInt(number) - BigInt(2)) : BigInt(1);
      }
    }
    
    console.log(factorials)
    //multiply results 
    for (let index = 0; index < factorials.length; index++) {
      result *= BigInt(factorials[index])
    }
    console.log(result)
    if (String(result).match(/[0]+\b/g) === null) {
      return 0
    } else {
      return String(result).match(/[0]+\b/g)[0].length
    }
  }
  