class_docstr: A range represents a start and end points for indexing a shard
  from a full tensor.
code: def __init__(self, start, end):
      self.start = start
      self.end = end
      self.size = end - start
  
imports: from apex.optimizers import FusedAdam
  import math
  import torch
  from megatron import get_args
  from megatron import get_timers
  from megatron import print_rank_0
  from megatron.core import mpu, tensor_parallel
  from .optimizer import MixedPrecisionOptimizer, _zero_grad_group_helper
  from .utils import shard_buffer
label_desc: Use image node_id 1 to create a new Range object  with example: obj = Range(start, end)