import builtins

string = 'angstrom'

all_builtins = dir(builtins)
# because we have kilobytes, other bytes we have to remove bytes
all_builtins.remove("bytes")
# have to deal with octet as well
all_builtins.remove("oct")
# have to remove min which is short for minute
all_builtins.remove("min")
for builtin in all_builtins:
    if builtin in string:
        raise RuntimeError(f"String parsing error for `{string}`. Enter a string accepted by quantities")