<a href="#Constants">integer constant</a>.
An optional prefix sets a non-decimal base: <code>0b</code> or <code>0B</code>
for binary, <code>0</code>, <code>0o</code>, or <code>0O</code> for octal,
and <code>0x</code> or <code>0X</code> for hexadecimal
[<a href="#Go_1.13">Go 1.13</a>].
A single <code>0</code> is considered a decimal zero.
In hexadecimal literals, letters <code>a</code> through <code>f</code>