def create_grant(KeyId=None, GranteePrincipal=None, RetiringPrincipal=None,
    Operations=None, Constraints=None, GrantTokens=None, Name=None):
    """
    Adds a grant to a key to specify who can use the key and under what conditions. Grants are alternate permission mechanisms to key policies.
    For more information about grants, see Grants in the AWS Key Management Service Developer Guide .
    See also: AWS API Documentation
    
    Examples
    The following example creates a grant that allows the specified IAM role to encrypt data with the specified customer master key (CMK).
    Expected Output:
    
    :example: response = client.create_grant(
        KeyId='string',
        GranteePrincipal='string',
        RetiringPrincipal='string',
        Operations=[
            'Decrypt'|'Encrypt'|'GenerateDataKey'|'GenerateDataKeyWithoutPlaintext'|'ReEncryptFrom'|'ReEncryptTo'|'CreateGrant'|'RetireGrant'|'DescribeKey',
        ],
        Constraints={
            'EncryptionContextSubset': {
                'string': 'string'
            },
            'EncryptionContextEquals': {
                'string': 'string'
            }
        },
        GrantTokens=[
            'string',
        ],
        Name='string'
    )
    
    
    :type KeyId: string
    :param KeyId: [REQUIRED]
            The unique identifier for the customer master key (CMK) that the grant applies to.
            To specify this value, use the globally unique key ID or the Amazon Resource Name (ARN) of the key. Examples:
            Globally unique key ID: 12345678-1234-1234-1234-123456789012
            Key ARN: arn:aws:kms:us-west-2:123456789012:key/12345678-1234-1234-1234-123456789012
            

    :type GranteePrincipal: string
    :param GranteePrincipal: [REQUIRED]
            The principal that is given permission to perform the operations that the grant permits.
            To specify the principal, use the Amazon Resource Name (ARN) of an AWS principal. Valid AWS principals include AWS accounts (root), IAM users, IAM roles, federated users, and assumed role users. For examples of the ARN syntax to use for specifying a principal, see AWS Identity and Access Management (IAM) in the Example ARNs section of the AWS General Reference .
            

    :type RetiringPrincipal: string
    :param RetiringPrincipal: The principal that is given permission to retire the grant by using RetireGrant operation.
            To specify the principal, use the Amazon Resource Name (ARN) of an AWS principal. Valid AWS principals include AWS accounts (root), IAM users, federated users, and assumed role users. For examples of the ARN syntax to use for specifying a principal, see AWS Identity and Access Management (IAM) in the Example ARNs section of the AWS General Reference .
            

    :type Operations: list
    :param Operations: A list of operations that the grant permits.
            (string) --
            

    :type Constraints: dict
    :param Constraints: A structure that you can use to allow certain operations in the grant only when the desired encryption context is present. For more information about encryption context, see Encryption Context in the AWS Key Management Service Developer Guide .
            EncryptionContextSubset (dict) --A list of key-value pairs, all of which must be present in the encryption context of certain subsequent operations that the grant allows. When certain subsequent operations allowed by the grant include encryption context that matches this list or is a superset of this list, the grant allows the operation. Otherwise, the grant does not allow the operation.
            (string) --
            (string) --
            
            EncryptionContextEquals (dict) --A list of key-value pairs that must be present in the encryption context of certain subsequent operations that the grant allows. When certain subsequent operations allowed by the grant include encryption context that matches this list, the grant allows the operation. Otherwise, the grant does not allow the operation.
            (string) --
            (string) --
            
            

    :type GrantTokens: list
    :param GrantTokens: A list of grant tokens.
            For more information, see Grant Tokens in the AWS Key Management Service Developer Guide .
            (string) --
            

    :type Name: string
    :param Name: A friendly name for identifying the grant. Use this value to prevent unintended creation of duplicate grants when retrying this request.
            When this value is absent, all CreateGrant requests result in a new grant with a unique GrantId even if all the supplied parameters are identical. This can result in unintended duplicates when you retry the CreateGrant request.
            When this value is present, you can retry a CreateGrant request with identical parameters; if the grant already exists, the original GrantId is returned without creating a new grant. Note that the returned grant token is unique with every CreateGrant request, even when a duplicate GrantId is returned. All grant tokens obtained in this way can be used interchangeably.
            

    :rtype: dict
    :return: {
        'GrantToken': 'string',
        'GrantId': 'string'
    }
    
    
    """
    pass
