Concatenate block managers into one.

    Parameters
    ----------
    mgrs_indexers : list of (BlockManager, {axis: indexer,...}) tuples
    axes : list of Index
    concat_axis : int
    copy : bool

def concatenate_block_managers(mgrs_indexers, axes, concat_axis, copy):
    """
    Concatenate block managers into one.

    Parameters
    ----------
    mgrs_indexers : list of (BlockManager, {axis: indexer,...}) tuples
    axes : list of Index
    concat_axis : int
    copy : bool

    """
    concat_plans = [get_mgr_concatenation_plan(mgr, indexers)
                    for mgr, indexers in mgrs_indexers]
    concat_plan = combine_concat_plans(concat_plans, concat_axis)
    blocks = []

    for placement, join_units in concat_plan:

        if len(join_units) == 1 and not join_units[0].indexers:
            b = join_units[0].block
            values = b.values
            if copy:
                values = values.copy()
            elif not copy:
                values = values.view()
            b = b.make_block_same_class(values, placement=placement)
        elif is_uniform_join_units(join_units):
            b = join_units[0].block.concat_same_type(
                [ju.block for ju in join_units], placement=placement)
        else:
            b = make_block(
                concatenate_join_units(join_units, concat_axis, copy=copy),
                placement=placement)
        blocks.append(b)

    return BlockManager(blocks, axes)