code: function inlineDiff (actual, expected, formatAdd, formatRem) {
    var result = diff.diffWordsWithSpace(actual, expected)
      .map(function (line, idx) {
        if (line.added) { return formatLinesWith(formatAdd, line.value) }
        return line.removed
          ? formatLinesWith(formatRem, line.value)
          : line.value
      })
      .join('')
  
    var lines = result.split('\n')
    if (lines.length > 4) {
      result = lines
        .map(function (line, idx) {
          return lpad(idx + 1, String(lines.length).length) + ' | ' + line
        })
        .join('\n')
    }
  
    return formatRem('actual') + ' ' + formatAdd('expected') + '\n\n' + result
  }
docs: Return inline diff of actual vs expected.
  
  @param {*} actual Actual value
  @param {*} expected Expected value
  @param {function} formatAdd Addition formatter
  @param {function} formatRem Removal formatter
  @return {string}