Violation of interface PricingStrategy

[rstormsf]

https://github.com/TokenMarketNet/ico/blob/master/contracts/PricingStrategy.sol

the contract is being used as an interface.
In Solidity, there is keyword: interface which must be used instead of contract
Also, it shouldn't have any state variables and any implementations of any methods.

Probably more accurate comment would be either:
using interface or abstract contract

Abstract contract can't also have any implementations.
So in your case it's not either an interface nor contract.

So please choose how you want it to behave.

https://solidity.readthedocs.io/en/develop/contracts.html#abstract-contracts

Interfaces
Interfaces are similar to abstract contracts, but they cannot have any functions implemented. There are further restrictions:

Cannot inherit other contracts or interfaces.
Cannot define constructor.
Cannot define variables.
Cannot define structs.
Cannot define enums.