code: function matchLicense (licenseString) {
    // Find all textual matches on license text.
    var normalized = normalizeText(licenseString)
    var matchingLicenses = []
  
    var license
  
    // Check matches of normalized license content against signatures.
    for (var i = 0; i < licenses.length; i++) {
      license = licenses[i]
      var match = false
      for (var j = 0; j < license.signatures.length; j++) {
        if (normalized.indexOf(license.signatures[j]) >= 0) {
          match = true
          break
        }
      }
      if (match) {
        matchingLicenses.push(license)
      }
    }
    // For single-line license, check if it's a known license id.
    if (matchingLicenses.length === 0 && !/[\n\f\r]/.test(licenseString) && licenseString.length < 100) {
      var licenseName = normalizeText(licenseString)
      // If there's an extra "license" on the end of the name, drop it ("MIT License" -> "MIT").
      license = licenseIndex[licenseName] || licenseIndex[licenseName.replace(/ licen[sc]e$/, '')]
      if (!license) {
        license = {name: licenseName, id: null}
      }
      matchingLicenses.push(license)
    }
    if (matchingLicenses.length === 0) {
      return null
    }
    if (matchingLicenses.length > 1) {
      console.warn('Multiple matching licenses: ' + matchingLicenses.length, [licenseString, matchingLicenses])
    }
    return matchingLicenses[0]
  }
docs: Match a license body or license id against known set of licenses.