code: def get_block_hash(block_height, coin_symbol='btc', api_key=None):
      '''
      Takes a block_height and returns the block_hash
      '''
      return get_block_overview(block_representation=block_height,
              coin_symbol=coin_symbol, txn_limit=1, api_key=api_key)['hash'f get_block_hash(block_height, coin_symbol='btc', api_key=None):
      '''
      Takes a block_height and returns the block_hash
      '''
      return get_block_overview(block_representation=block_height,
              coin_symbol=coin_symbol, txn_limit=1, api_key=api_key)['hash']
docs: Takes a block_height and returns the block_hash