Add Iteration base class (#3472)

[Nic-Ma]

• [DLMED] add Iteration base class

Signed-off-by: Nic Ma nma@nvidia.com

• [DLMED] update according to comments

Signed-off-by: Nic Ma nma@nvidia.com

• [DLMED] update according to comments

Signed-off-by: Nic Ma nma@nvidia.com

Fixes # .

Description

A few sentences describing the changes proposed in this pull request.

Status

Ready/Work in progress/Hold

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.