Binary to Decimal Converter

In this lab, your task is to write a Python function named convert_binary that converts a binary string to its decimal equivalent. The key constraint is to achieve this without using any built-in methods for direct conversion.

Function Requirements

• The function should be named convert_binary.
• It must accept a binary string (e.g., 0b1010) as input.
• The function should return the decimal equivalent of the binary string.

Examples

1. Input: '0b101'
   Output: 5

2. Input: '0b1111'
   Output: 15

3. Input: '0b0'
   Output: 0

Notes

• Ensure that your function can handle various lengths of binary strings.
• Remember, the use of direct binary-to-decimal conversion functions provided by Python is not allowed. You need to implement the conversion logic manually.