def list_correlated_data(correlated_data):
    """Creates a list of data entities from correlated data tuple.

    Parameters
    -----------
	correlated_data : tuple
        Tuple of data columns with high correlation.

   Returns
   --------
    list
        List of data columns correlated at least once.
    """

    data_list = []

    # Iterate over correlated data, add second value to list if not present.
    for correlation in correlated_data:

        # Data item to be removed is 2nd item in tuple.
        data_item = correlation[1]

        if data_list.__contains__(data_item):
            pass

        else:
            data_list.append(data_item)

    # Return list.
    return data_list