_me-calc-processing( current-property, operation, fallback )
    prop = current-property[ 0 ]
    operation = unquote( operation )
    if fallback
        add-property( prop, fallback )
    for prefix in caniuse-prefixes( "calc" )
        add-property( prop, s( "-%s-calc(%s)", prefix, operation ) )
    s( "calc(%s)", operation )

me-calc( operation, fallback = false )
    if current-property
        _me-calc-processing( current-property, operation, fallback )
    else
        error( "me-calc() must be used within a property" )

unless me-no-conflict
    calc( operation, fallback = false )
        if current-property
            _me-calc-processing( current-property, operation, fallback )
        else
            error( "calc() must be used within a property" )