Add list.count

[virendrakabra14]

Adds list.count method. Completes a part of #941.

1. For incompatible types, an error is raised. Should we return count 0 instead?
2. I am not sure in which file to add the test-cases, but I tried the following test locally:

def test_List():
    a: list[i32]
    a = [1, 2, 3]

    # print(a.count(1.0)) # semantic error: Type mismatch in 'count', the types must be compatible
    print(a.count(-1))
    print(a.count(2))
    a.append(2)
    print(a.count(2))
    a.remove(2)
    print(a.count(2))

test_List()

0
1
2
1

[czgdp1807]

Nice. Please add an integration test as well for list.count. See test_list_*.py in https://github.com/lcompilers/lpython/tree/main/integration_tests for the pattern of testing lists and use your creativity for writing strong test for list.count (for example l.count where l can be empty, check l.count after every insertion/deletion in a loop, etc.)

[czgdp1807]

1. For incompatible types, an error is raised. Should we return count 0 instead?

I would prefer an error. For testing error see https://github.com/lcompilers/lpython/tree/main/tests/errors and following pattern for registering error tests,

lpython/tests/tests.toml

Lines 66 to 68 in b35e744

	[[test]]
	filename = "errors/type_mismatch.py"
	asr = true

[Shaikh-Ubaid]

I think your commits are including previous changes (already merged/present in latest main branch).

[Shaikh-Ubaid]

To remove extra commits (already present in main), you can rebase over main branch.

For example, first update your main branch:

git checkout main
git pull

Now switch to your branch and rebase:

git checkout scratch
git rebase main

Now force push it

git push your_remote scratch --force-with-lease

[virendrakabra14]

Thanks @Shaikh-Ubaid. Will use this in future.

[czgdp1807]

Suggested change

	while len(x)>0:
	while len(x) > 0:

[czgdp1807]

Good that you figured it out on your own.

[certik]

For now this is good. Later we should lift this into ASR and implement there, it will be a lot easier to maintain.

[certik]

This is good, thanks!

It has been addressed.