code: public static String mapToID(final String aBasePath, final String aPtPath) throws InvalidPathException {
          return mapToID(removeBasePath(aBasePath, aPtPath));
      }
docs: Maps the supplied base path to an ID using the supplied Pairtree path.
  
  @param aBasePath A base path to use for the mapping
  @param aPtPath A Pairtree path to map to an ID
  @return The ID that is a result of the mapping
  @throws InvalidPathException If there is trouble mapping the path