>>> from notes import busca_dni

>>> l = [['44444444D',8.3],['11111111A',7.25],['88888888H',4.1],['22222222B',3.8]]
>>> busca_dni(l,'88888888H')
True
>>> busca_dni(l,'33333333C')
False
>>> busca_dni([],'11111111A')
False