runtime.py

def duration(sec):
    is_float = isinstance(sec, float)
    parts = [
        ('days', int(sec / 86400)),
        ('hours', int((sec % 86400) / 3600)),
        ('minutes', int((sec % 3600) / 60)),
        ('seconds', float(sec % 60) if is_float else int(sec % 60))
    ]
    for i in range(len(parts)):
        if float(parts[i][1]) > 0:
            break
    return ":".join([*list(map(lambda x: f"{x[1]:02}{x[0][0]}", parts[i:-1])), f"{parts[-1][1]:06.3f}{parts[-1][0][0]}" if is_float else f"{parts[-1][1]:02}{parts[-1][0][0]}"]).lstrip('0')

print(duration(1))
print(duration(120.123532))
print(duration(1445))
print(duration(101445))