from typing import List


def snip_out(file_str:str, start_key:str)->str:
    """From an anvil.yaml file, snips out only the string you want: the database description."""
    good_string:List[str]=[]
    save_this_one = False
    for line in file_str.split('\n'):
        if line.startswith(start_key):
            good_string.append(line)
            save_this_one=True
        elif save_this_one is False:
            continue
        elif line[0]==' ' or line[0]=='\t':
            good_string.append(line)
        else:
            save_this_one=False
    return '\n'.join(good_string)