GET
api/v1/order_book/best_bonds/

[{'bid_price': 1400.0,
  'currency': 'EUR',
  'issuer': 'test_issuer_name_2',
  'nominal_price': 1500.0,
  'offer_price': 1600.0,
  'security_definition_id': 6,
  'symbol': 'test_security_definition_2'}]


-----------------------------------------------------------

GET
api/v1/order_book/best_equities/

[{'bid_price': 140.0,
  'currency': 'BYN',
  'issuer': 'test_issuer_name_1',
  'nominal_price': 500.0,
  'offer_price': 160.0,
  'security_definition_id': 5,
  'symbol': 'test_security_definition_1'},
 {'bid_price': 130.0,
  'currency': 'BYN',
  'issuer': 'test_issuer_name_3',
  'nominal_price': 500.0,
  'offer_price': 170.0,
  'security_definition_id': 7,
  'symbol': 'test_security_definition_3'}]