some.py

def get_dataset(filehandle, start_dataset,end_dataset): # dataset_type : Dataset_01, Dataset_02, Dataset_03 or Dataset_04
    dataset = ""
    with open(filehandle) as lines:
        for num, line in enumerate(lines, 1):
            if start_dataset in line:
                start_pos = num
            if end_dataset in line:
                end_pos = num
    lines = open(filehandle).readlines()
    for x in range(start_pos, end_pos-1):
        lines[x] = lines[x].replace(" ", "")
        #lines[x] = lines[x].replace("\n", "")
        if("#" not in lines[x] and lines[x][0] != "\n"):
            dataset += lines[x]
    return dataset.split("\n")

file_url = "datasets.txt"
start_d = 'D2'
end_d = 'D3'
print(get_dataset(file_url,start_d, end_d))