Sass check if value is passed to mixin - variables

Question

Please help me to modify mixin and create compatible function.
Here is my mixin, it can accept optonal parameter !important true or false, and if !important is true then output height as
height: 16px !important; for example:
#mixin svg-size($size, !important: true) {
svg {
height: $size foo();
width: $size foo();
}
}
Call mixin:
#include svg-size(16px, true);
Output:
svg {
height: 16px !important;
width: 16px !important;
}
I also need a proper name for that kind of function

Answer 1

How about conditionally-important as the function name and use some basic at-rules for flow control returning !important if true?
#function conditionally-important ($important) {
#if $important {
#return !important;
}
#return null;
}
#mixin svg-size($size, $is-important: true) {
svg {
height: $size conditionally-important($is-important);
width: $size conditionally-important($is-important);
}
}
// Calling as important
#include svg-size(16px, true);
// Output
svg {
height: 16px !important;
width: 16px !important;
}
// Calling as not important
#include svg-size(16px, false);
// Output
svg {
height: 16px;
width: 16px;
}