Here is an implementation of the safe repr for numbers if helpful:

```
def safe_repr_int(object):
    sign = ''
    if object < 0:
        sign = '-'
        object  = -object
    r = repr(object)
    if len(r) <= 4:
        return sign + r
    parts = [sign]
    left = len(r) % 3
    if left:
        parts.append(r[0:left])
        parts.append('_')
        r = r[left:]
    parts.append(r[0:3])
    for i in range(3, len(r), 3):
        parts.append('_')
        parts.append(r[i:i + 3])
    return ''.join(parts)
```