first program code review: https://www.reddit.com/r/Python/comments/6rvd0v/first_time_properly_getting_into_coding_how_is/

first.py

#!/bin/env python

# doing little more than applying my suggestions to the
#  first-time coding effort of:
#  https://www.reddit.com/r/Python/comments/6rvd0v/first_time_properly_getting_into_coding_how_is/

#  There is more which can be done / said here (e.g. EOF-quit handling), but this
#  shows the suggestions I put forth applied, and the effect of separating getting input
#  from forming the calculation.

import sys

def get_integer(prompt=None):
    quitters = ('q', 's')
    quitting = lambda s: s.lower().startswith(quitters)

    if prompt is None:
        prompt = "Value to test compliance with Colatz Conjecture: "
    err_prompt = 'Enter an integer greater than zero, or "quit"'

    while True:
        s = input(prompt)
        if quitting(s):
            sys.exit(0)
        try:
            i = int(s)
        except:
            print(err_prompt)
            continue

        if i > 0:
            yield i
        else:
            print(err_prompt)


x = 0
even = lambda x: x%2==0

for x in get_integer():
    print(f'in: {x}')
    i = 0  # number of calculations
    while x != 1:
        x = x//2 if even(x) else 3*x+1
        i += 1

    print(f'out: {x}, {i}')