src/Robin/Ntlm/Crypt/Hasher/AbstractHasher.php
protected function validateHashContext($context)
    {
        if (!($context instanceof HashContext) && (false === $context
            || !is_resource($context)
            || (is_resource($context) && static::HASH_CONTEXT_RESOURCE_TYPE !== get_resource_type($context)))) {
            throw new InvalidArgumentException(
                'Unable to initialize hashing context. Your system might not support the supplied algorithm.'
            );
        }

        return $context;
    }
protected function validateHashContext($context)
    {
        if (!($context instanceof HashContext) && (false === $context
            || !is_resource($context)
            || (is_resource($context) && static::HASH_CONTEXT_RESOURCE_TYPE !== get_resource_type($context)))) {
            throw new InvalidArgumentException(
                'Unable to initialize hashing context. Your system might not support the supplied algorithm.'
            );
        }

        return $context;
    }
Validates a given incremental hashing context.

@link http://php.net/manual/en/hash.resources.php
@param mixed $context The context to validate.
@return resource|HashContext The incremental hashing context.
@throws InvalidArgumentException If the hash context isn't valid.