use index to search for first occurrance of one element
list.index(element), list.index(element, start, end) element can be found from start position or start and end position can be given
list_numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
element = 7
list_numbers.index(element)
list_numbers.index(element, 1, 5)
enumerate the list
list_numbers = [3, 1, 2, 3, 3, 4, 5, 6, 3, 7, 8, 9, 10]
[i for i, n in enumerate(list_numbers) if n == 3] # List comprehension
list_numbers = [3, 1, 2, 3, 3, 4, 5, 6, 3, 7, 8, 9, 10]
g = (i for i, n in enumerate(list_numbers) if n == 3) # Generator expression
print("Generators store values, the first value here is:", next(g), ". Then the next is:", next(g), "followed by ", next(g),"and finally ", next(g))