@_infer_type.register(irast.Coalesce)
def __infer_coalesce(ir, schema):
    result = _infer_common_type([ir.left, ir.right], schema)
    if (result is None):
        raise ql_errors.EdgeQLError('coalescing operator must have operands of related types', context=ir.context)
    return result
@_infer_type.register(irast.Coalesce)
def __infer_coalesce(ir, schema):
    result = _infer_common_type([ir.left, ir.right], schema)
    if (result is None):
        raise ql_errors.EdgeQLError('coalescing operator must have operands of related types', context=ir.context)
    return result