code: function summarizeFileCoverage(fileCoverage) {
      var ret = blankSummary();
      addDerivedInfoForFile(fileCoverage);
      ret.lines = computeSimpleTotals(fileCoverage, 'l');
      ret.functions = computeSimpleTotals(fileCoverage, 'f');
      ret.statements = computeSimpleTotals(fileCoverage, 's');
      ret.functions = computeSimpleTotals(fileCoverage, 'f', 'fnMap');
      ret.statements = computeSimpleTotals(fileCoverage, 's', 'statementMap');
      ret.branches = computeBranchTotals(fileCoverage);
      return ret;
    }
docs: returns the summary metrics given the coverage object for a single file. See `blankSummary()`
  to understand the format of the returned object.
  
  @method summarizeFileCoverage
  @static
  @param {Object} fileCoverage the coverage object for a single file.
  @return {Object} the summary metrics for the file