[:,0:3] python code example
Example 1: python array index range
a[start:stop] # items start through stop-1
a[start:] # items start through the rest of the array
a[:stop] # items from the beginning through stop-1
a[:] # a copy of the whole array
Example 2: python3 slice
# array[start:stop:step]
# start = include everything STARTING AT this idx (inclusive)
# stop = include everything BEFORE this idx (exclusive)
# step = (can be committed) difference between each idx in the sequence
arr = ['a', 'b', 'c', 'd', 'e']
arr[2:] => ['c', 'd', 'e']
arr[:4] => ['a', 'b', 'c', 'd']
arr[2:4] => ['c', 'd']
arr[0:5:2] => ['a', 'c', 'e']
arr[:] => makes copy of arr