<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def signed_to_float(hex: str) -> float: """Convert signed hexadecimal to floating value."""

    if int(hex, 16) & 0x8000:
        return -(int(hex, 16) & 0x7FFF) / 10
    else:
        return int(hex, 16) / 10