def set_metadata_index_and_column_names(dim, meta_df):
    """
    Sets index and column names to GCTX convention.
    Input:
        - dim (str): Dimension of metadata to read. Must be either "row" or "col"
        - meta_df (pandas.DataFrame): data frame corresponding to metadata fields
            of dimension specified.
    Output:
        None
    """
    if dim == "row":
        meta_df.index.name = "rid"
        meta_df.columns.name = "rhd"
    elif dim == "col":
        meta_df.index.name = "cid"
        meta_df.columns.name = "chd"