code: def fromsparse(a, order="C", fill_value=None):
      a = tensor(a)
      if not a.issparse():
          return a.astype(a.dtype, order=order, copy=False)
  
      tensor_order = get_order(
          order,
          None,
          available_options="CF",
          err_msg="only 'C' or 'F' order is permitted",
      )
      op = SparseToDense(
          dtype=a.dtype,
          gpu=a.op.gpu,
          order=order,
          fill_value=fill_value,
      )
      return op(a, order=tensor_order)
  
file_path: mars/mars/tensor/datasource/from_sparse.py
imports: from ...None import opcodes
  from ...serialization.serializables import KeyField, StringField, AnyField
  from ..array_utils import as_same_device, device, get_array_module
  from ..utils import get_order
  from .core import TensorHasInput
  from .array import tensor
label_desc: Use image node_id 1 for calling a global function with example usage: fromsparse(a, order, fill_value) and returns: op, a