function __construct($abstract, $concrete)
{
parent::__construct("Invalid binding {$abstract} to {$concrete}");
}
function __construct($abstract, $context)
{
parent::__construct("{$abstract} not bound in context {$context}");
}
function __construct($abstract, $concrete, $context, $existing)
{
parent::__construct("Cannot bind {$abstract} to {$concrete} in context {$context}. Already bound to {$existing}");
}