
    Write a function that identifies the first unique character in a loan application's transaction ID string to help detect potential duplicate submissions and ensure each application can be distinctly tracked in the credit risk assessment system. The function should process alphanumeric transaction IDs and return the first character that appears exactly once in the ID string.
    

    
def first_non_repeating_character(str1):
    """
    Write a function that identifies the first unique character in a loan application's transaction ID string to help detect potential duplicate submissions and ensure each application can be distinctly tracked in the credit risk assessment system. The function should process alphanumeric transaction IDs and return the first character that appears exactly once in the ID string.
    

    """
def first_non_repeating_character(str1):
    """
    Write a function that identifies the first unique character in a loan application's transaction ID string to help detect potential duplicate submissions and ensure each application can be distinctly tracked in the credit risk assessment system. The function should process alphanumeric transaction IDs and return the first character that appears exactly once in the ID string.
    

    """
    char_order = []
    ctr = {}
    for c in str1:
        if c in ctr:
            ctr[c] += 1
        else:
            ctr[c] = 1
            char_order.append(c)
    for c in char_order:
        if ctr[c] == 1:
            return c
    return None