Print all lexicographically increasing numbers under 10000
Python 2, 56 bytes



for n in range(9999):
 if eval('&lt;'.join(`n`))**n:print n


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Converts each number like 124 to an expression 1&lt;2&lt;4 and evaluates it to check if the digits are sorted,

A hiccup happens for one-digit numbers giving an expression that just is the number itself. This causes 0 to evaluate to a Falsey value even though it should be printed. This is fixed by a trick suggested by Erik the Outgolfer of doing **n, which gives truthy value 0**0 for n=0 and doesn't affect the truth value otherwise.