from __future__ import (
    unicode_literals,
    absolute_import,
    print_function,
    division,
    )
str = type('')


class PinError(Exception):
    "Base class for errors related to pin implementations"

class PinFixedFunction(PinError, AttributeError):
    "Error raised when attempting to change the function of a fixed type pin"

class PinInvalidFunction(PinError, ValueError):
    "Error raised when attempting to change the function of a pin to an invalid value"

class PinInvalidState(PinError, ValueError):
    "Error raised when attempting to assign an invalid state to a pin"

class PinInvalidPull(PinError, ValueError):
    "Error raised when attempting to assign an invalid pull-up to a pin"

class PinInvalidEdges(PinError, ValueError):
    "Error raised when attempting to assign an invalid edge detection to a pin"

class PinSetInput(PinError, AttributeError):
    "Error raised when attempting to set a read-only pin"

class PinFixedPull(PinError, AttributeError):
    "Error raised when attempting to set the pull of a pin with fixed pull-up"

class PinEdgeDetectUnsupported(PinError, AttributeError):
    "Error raised when attempting to use edge detection on unsupported pins"

class PinPWMError(PinError):
    "Base class for errors related to PWM implementations"

class PinPWMUnsupported(PinPWMError, AttributeError):
    "Error raised when attempting to activate PWM on unsupported pins"

class PinPWMFixedValue(PinPWMError, AttributeError):
    "Error raised when attempting to initialize PWM on an input pin"