def backup_key(vault_base_url, key_name, custom_headers:nil)
      response = backup_key_async(vault_base_url, key_name, custom_headers:custom_headers).value!
      response.body unless response.nil?
    end
def backup_key(vault_base_url, key_name, custom_headers:nil)
      response = backup_key_async(vault_base_url, key_name, custom_headers:custom_headers).value!
      response.body unless response.nil?
    end
Requests that a backup of the specified key be downloaded to the client.

 The Key Backup operation exports a key from Azure Key Vault in a protected
 form. Note that this operation does NOT return key material in a form that
 can be used outside the Azure Key Vault system, the returned key material is
 either protected to a Azure Key Vault HSM or to Azure Key Vault itself. The
 intent of this operation is to allow a client to GENERATE a key in one Azure
 Key Vault instance, BACKUP the key, and then RESTORE it into another Azure
 Key Vault instance. The BACKUP operation may be used to export, in protected
 form, any key type from Azure Key Vault. Individual versions of a key cannot
 be backed up. BACKUP / RESTORE can be performed within geographical
 boundaries only; meaning that a BACKUP from one geographical area cannot be
 restored to another geographical area. For example, a backup from the US
 geographical area cannot be restored in an EU geographical area. This
 operation requires the key/backup permission.

 @param vault_base_url [String] The vault name, for example
 https://myvault.vault.azure.net.
 @param key_name [String] The name of the key.
 @param custom_headers [Hash{String => String}] A hash of custom headers that
 will be added to the HTTP request.

 @return [BackupKeyResult] operation results.