Generated by SassMeister.com, the Sass playground.

SassMeister-input.scss

// Sass v3.2.7
// Breakpoint v1.3

@import "breakpoint";

@function color() {
    $context: breakpoint-get-context(min-width);
    @if $context == 550px {
        @return blue;
    }
    @if $context == 850px {
        @return green;
    }
    @else {
        @return false;
    }
}

foo {
    @include breakpoint(550px) {
        color: color();
    }
}

SassMeister-output.css

@media (min-width: 550px) {
  foo {
    color: blue;
  }
}