def renamecol(X, old, new):
    """
    Rename column of a numpy ndarray with structured dtype, in-place.

    Implemented by the tabarray method 
    :func:`tabular.tab.tabarray.renamecol`.

    **Parameters**

            **X** :  numpy ndarray with structured dtype

                    The numpy array for which a column is to be renamed.

            **old** :  string

                    Old column name, e.g. a name in `X.dtype.names`.

            **new** :  string

                    New column name to replace `old`.

    """
    NewNames = tuple([n if n != old else new for n in X.dtype.names])
    X.dtype.names = NewNames