text: 
  
  const esgraph = require('esgraph')
  const esprima = require('esprima')
  
  /**
   * returns a dot graph as string
   * @param {A code string as string} sourceCode 
   */
  function app(sourceCode) {
    if (typeof sourceCode !== 'string') throw new Error('Param "sourceString" should be code string')
    try {
  
      const cfgObj = esgraph(esprima.parse(sourceCode, { range: true }))
      const dotstr = esgraph.dot(cfgObj, { counter: 0, source: sourceCode })
      return dotstr
  
    } catch (e) { return '' }
  }
  
  module.exports = app
  