code: def inlink_file(self, filepath):
          
          if not os.path.exists(filepath):
              logger.debug("Creating symbolic link to not existent file %s" % filepath)
  
          # Extract the Abinit extension and add the prefix for input files.
          root, abiext = abi_splitext(filepath)
  
          infile = "in_" + abiext
          infile = self.indir.path_in(infile)
  
          # Link path to dest if dest link does not exist.
          # else check that it points to the expected file.
          self.history.info("Linking path %s --> %s" % (filepath, infile))
  
          if not os.path.exists(infile):
              os.symlink(filepath, infile)
          else:
              if os.path.realpath(infile) != filepath:
                  raise self.Error("infile %s does not point to filepath %s" % (infile, filepath))
docs: Create a symbolic link to the specified file in the
          directory containing the input files of the task.