def plugin_has_provider?(namespace, plugin_type, provider)
    get_hash([ :load_info, namespace, sanitize_id(plugin_type) ]).has_key?(sanitize_id(provider))
  end
def plugin_has_provider?(namespace, plugin_type, provider)
    get_hash([ :load_info, namespace, sanitize_id(plugin_type) ]).has_key?(sanitize_id(provider))
  end
Check if a specified plugin provider has been loaded

 * *Parameters*
   - [String, Symbol] *namespace*  Namespace that contains plugin types
   - [String, Symbol] *plugin_type*  Plugin type name to check
   - [String, Symbol] *provider*  Plugin provider name to check

 * *Returns*
   - [Boolean]  Returns true if plugin provider has been loaded, false otherwise

 * *Errors*

 See:
 - Nucleon::Config#get_hash

 See also:
 - #sanitize_id