Error with calculator type program in python ValueError
<p>this is my script, i am new to python but have come to get this, please be forgiving as such in the answers and keep in mind that i am new to this.</p>

<pre><code>import functools
numbers=[]

def means():
    end_mean = functools.reduce(lambda x, y: x + y, numbers) / len(numbers)
    print(end_mean)

def sum():
    end_sum = functools.reduce(lambda x, y: x + y, numbers)
    print(end_sum)

def whatDo():
        print('Input Extra Numbers '+str(len(numbers)+1)+' (or nothing to close):')
        try:
            number= int(input())
            numbers.append(number)
        except:
            print('What do you want to do?')
            answer = input()
            if answer == "mean":
                means()

while True:
    print('Input Number '+str(len(numbers)+1)+' (or nothing to close):')
    try:
        number= int(input())
        numbers.append(number)
    except:
        print('What do you want to do?')
        answer = input()
        if answer == "mean":
            means()
            print('Do you want anything else?')
            reply=input()
            if reply=='no':
                break
            elif reply--'yes':
                whatDo()
        else:
            break
</code></pre>

<p>However i get this:</p>

<pre><code>Traceback (most recent call last):
  File "E:/Python/calculator.py", line 26, in &lt;module&gt;
    number= int(input())
ValueError: invalid literal for int() with base 10: ''

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "E:/Python/calculator.py", line 37, in &lt;module&gt;
    elif reply--'yes':
TypeError: bad operand type for unary -: 'str'
</code></pre>

<p>after the 'Do you want anything else' and i enter 'yes'.</p>

<p><code>elif reply--'yes':</code> should be <code>elif reply == 'yes':</code></p>

python