Floating point numbers can be formatted at compile time

Example:
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import std.format : format;
import std.math : sqrt;

enum pi = format!"%s"(3.1415926f);
static assert(pi == "3.14159");

enum golden_ratio = format!"|%+-20.10E|"((1 + sqrt(5.0)) / 2);
static assert(golden_ratio == "|+1.6180339887E+00   |");
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