code: function regexpForFunctionCall(fnName, args) {
    const optionalWhitespace = '\\s*';
    const argumentParts = args.map(
      arg => optionalWhitespace + arg + optionalWhitespace
    );
    let parts = [fnName, '\\(', argumentParts.join(','), '\\)'];
    return new RegExp(parts.join(''), 'g');
  }
docs: Create a regular expression to match a function call.
  
  @param fnName The name of the function being called. Can include
  property access (eg `console.log`)
  @param args An array of arguments we expect to find. Each of these
  can be a regular expression to match the expected type of argument, and can
  include capture groups.