docs: function checkPython () {
      log.verbose('check python', 'checking for Python executable "%s" in the PATH', python)
      which(python, function (err, execPath) {
        if (err) {
          log.verbose('`which` failed', python, err)
          if (python === 'python2') {
            python = 'python'
            return checkPython()
          }
          if (win) {
            guessPython()
          } else {
            failNoPython()
          }
        } else {
          log.verbose('`which` succeeded', python, execPath)
          // Found the `python` exceutable, and from now on we use it explicitly.
          // This solves #667 and #750 (`execFile` won't run batch files
          // (*.cmd, and *.bat))
          python = execPath
          checkPythonVersion()
        }
      })
    }