Copy J coupling data from one data pipe to another.
pipe_from: The name of the pipe to copy the J coupling data from.
pipe_to: The name of the pipe to copy the J coupling data to.
This function will copy J coupling data from one pipe to another.
To copy all J coupling data from pipe `DMSO' to pipe `CDCl3', type one of:
[numbers=none] relax> j_coupling.copy('DMSO', 'CDCl3')
[numbers=none] relax> j_coupling.copy(pipe_from='DMSO', pipe_to='CDCl3')