def count$\_0$s$\_1$s$($s$)$:

$\text{'}\text{'}\text{'}$

$$Check whether the input string $"$s$"$ is monotonic.

$\text{'}\text{'}\text{'}$

$$# TODO: Write your code to implement this function.

# $(1)$ Test your function with input string 'abc'. It should return None.

print$($count$\_0$s$\_1$s$(\text{'}$abc$\text{'}))$

#$>>>$ The input string must contain only $0$s and $1$s$!$

#$>>>$ None

# $(2)$ Test your function with input string $\text{'}1\text{'}.$ It should return $(0,1).$

print$($count$\_0$s$\_1$s$(\text{'}1\text{'}))$

#$>>>(0,1)$

# $(3)$ Test your function with an empty input string $\text{'}\text{'}.$ It should return None.

print$($count$\_0$s$\_1$s$(\text{'}\text{'}))$

#$>>>$ The input string must contain at least one $0$ or $1!$

#$>>>$ None

# $(4)$ Test your function with input string $\text{'}01\text{'}.$ It should return $(1,1).$

print$($count$\_0$s$\_1$s$(\text{'}01\text{'}))$

#$>>>(1,1)$

# $(5)$ Test your function with input string $\text{'}01010001\text{'}.$ It should return $(5,3).$

print$($count$\_0$s$\_1$s$(\text{'}01010001\text{'}))$

#$>>>(5,3)$