def get_header(chain: BaseChain, at_block: Union[str, int]) -> BlockHeader:
if at_block == 'pending':
raise NotImplementedError("RPC interface does not support the 'pending' block at this time")
elif at_block == 'latest':
at_header = chain.get_canonical_head()
elif at_block == 'earliest':
# TODO find if genesis block can be non-zero. Why does 'earliest' option even exist?
at_header = chain.get_canonical_block_by_number(0).header
# mypy doesn't have user defined type guards yet
# https://github.com/python/mypy/issues/5206
elif is_integer(at_block) and at_block >= 0: # type: ignore
at_header = chain.get_canonical_block_by_number(at_block).header
else:
raise TypeError("Unrecognized block reference: %r" % at_block)
return at_header
def get_block_at_number(chain: BaseChain, at_block: Union[str, int]) -> BaseBlock:
# mypy doesn't have user defined type guards yet
# https://github.com/python/mypy/issues/5206
if is_integer(at_block) and at_block >= 0: # type: ignore
# optimization to avoid requesting block, then header, then block again
return chain.get_canonical_block_by_number(at_block)
else:
at_header = get_header(chain, at_block)
return chain.get_block_by_header(at_header)