fix: more list comprehension and correct pipeline initialisation

[ringoldsdev]

This pull request refactors the Pipeline class in efemel/pipeline.py to simplify its implementation and improve readability while maintaining functionality. Key changes include replacing nested loops with generator expressions, updating type hints for better clarity, and streamlining methods for single-function application. Corresponding test cases in tests/test_pipeline.py have been updated to reflect these changes.

Pipeline Refactoring:

• Simplified Method Implementations:

  • Replaced nested loops with generator expressions in methods like __iter__, to_list, and flatten for improved readability and efficiency. (Faea2baaL99R99, Faea2baaL192R192)
  • Streamlined filter and map methods by directly using generator expressions for chunk processing. (Faea2baaL141R141)
  • Updated tap and each methods to use deque for efficient consumption of elements. (Faea2baaL172R172)

• Improved Type Hints:

  • Added Union type hints to support multiple types for source in the constructor and flatten method. (efemel/pipeline.pyL16-R19, Faea2baaL172R172)

• Refactored apply Method:

  • Simplified apply to handle only a single transformation function, removing support for multiple functions. (Faea2baaL301R301)

Test Updates:

• Updated Test Cases:
  • Removed tests for multi-function application and no-function application in apply, reflecting the refactored method's new behavior.
  • Renamed test for single-function application to test_apply_function for clarity.