code: function removeSrcDirPrefixFromFile( srcDir, file ) {
      if ( typeof srcDir !== 'string' ) return file;
      if ( typeof file !== 'string' ) return file;
  
      if ( file.substr( 0, srcDir.length ) !== srcDir ) {
          return file;
      }
      return file.substr( srcDir.length );
  }
docs: If present, remove the `srcDir` prefix of `file`.
  
  @param   {[type]} srcDir [description]
  @param   {[type]} file   [description]
  @returns {[type]}        [description]
  
  @example
  const f = removeSrcDirPrefixFromFile;
  f("/src/", "/myfile.cpp") === "/myfile.cpp";
  f("/src/", "/src/myfile2.cpp") === "myfile2.cpp";