datetime.isnat
datetime: TF = isnat (T)
Test for Not-A-Time elements in datetime array.
TF = isnat (T) returns a logical array TF of the
same size as T containing true for each corresponding
element of T that is Not-A-Time (NaT) and false
otherwise. NaT is the equivalent of NaN in numeric
arrays.
If T is not a datetime array, isnat returns an error.
Source Code: datetime