1. A method comprising: receiving a sequence of values of text elements; determining, with one or more computing devices, a score for a text element value of the sequence, where the score is related to the probability of a particular text element value equaling one or more given values, where said probability is based on sequences of text element values that are consistent with a defined format, and where determining the score with respect to the value of the particular text element in a particular sequence of text elements is related to how frequently the value of the particular text element follows same or similar sequences of the text element values that are consistent with the defined format; comparing, with the one or more computing devices, the score to a threshold; when the score is below a threshold, modifying, with the one or more computing devices, the value of the text element to form a modified sequence of text element values; processing, with the one or more computing devices, the modified sequence of text element values with a set of instructions; and testing, with the one or more computing devices, a performance characteristic of the set of instructions when the set of instructions process the modified sequence of text element values.