Turning closure output into dataframe in R

The following code generates an object of type 'closure'.

function (x, df1, df2, ncp, log = FALSE) 
{
  if (missing(ncp)) 
    .Call(C_df, x, df1, df2, log)
  else .Call(C_dnf, x, df1, df2, ncp, log)
}

The output looks like a typical dataframe. However, I cannot manipulate it like a dataframe since it's a function. Is there a way for me to take the output and turn it into a dataframe that I can manipulate and clean?