There are variations, like

    import ast
    code = """
import datetime
datetime.datetime.now()
"""
    tree = ast.parse(code)
    print(ast.dump(tree, indent=2))

the AST prints

Module(
  body=[
    Import(
      names=[
        alias(name='datetime')]),
    Expr(
      value=Call(
        func=Attribute(
          value=Attribute(
            value=Name(id='datetime', ctx=Load()),
            attr='datetime',
            ctx=Load()),
          attr='now',
          ctx=Load()),
        args=[],
        keywords=[]))],
  type_ignores=[])

Or using import from

    import ast
    code = """
from datetime import datetime
datetime.now()
"""
    tree = ast.parse(code)
    print(ast.dump(tree, indent=2))

Module(
  body=[
    ImportFrom(
      module='datetime',
      names=[
        alias(name='datetime')],
      level=0),
    Expr(
      value=Call(
        func=Attribute(
          value=Name(id='datetime', ctx=Load()),
          attr='now',
          ctx=Load()),
        args=[],
        keywords=[]))],
  type_ignores=[])

Is there a built-in way to determine what module the function call belongs to? That is find all function calls datetime.now() from datetime module?